JP2000027731A - Injection pipe for common rail - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection pipe for a common rail which can inject fuel stably while suppressing pressure fluctuation in an injection pipe, and show stable sealability at the connection part of the injection pipe. SOLUTION: In a common rail, a branch hole, having a pressure receiving seat surface communicated with a main pipe rail 1 and opened to the outside, is formed on a boss 1-4 on a peripheral wall of the main pipe rail 1. An injection pipe 2a is connected to the common rail by abutting a pressurizing seat surface 2a-2 serving as a connection head against the pressure receiving seat surface 13 and engaging therewith, fastening together with pressurizing under a neck of the connection head 2a-2 caused by screwing of a screwing nut 4. A metal ring 3a having an orifice 3a-1 is embedded in the connection head 2a-2 of the injection pipe 2a, without influencing on sealability by the metal ring 3a. Axial force by the fastening nut 4 incorporated in the injection pipe side is applied as force for fixing the metal ring 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an injection pipe connected to a common rail such as a high pressure fuel manifold or a block rail in a diesel internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, this type of connection structure between a common rail and an injection pipe is, for example, as shown in FIG. 7, provided with a plurality of spaced pipes provided on an axial peripheral wall of a main pipe rail 31 made of a circular pipe. The pressure receiving seat surface 31 which communicates with the boss portion 31-4 and communicates with the flow passage 31-1 of the main pipe rail 31 and opens outward.
-3 is formed, and the pressing seat surface 32-3 formed by the connection head 32-2 on the injection pipe 32 side is brought into contact with the pressure receiving seat surface 31-3 on the main pipe rail 31 side. The external screw nut 33 for tightening, which has been previously assembled on the injection pipe side, is screwed into the boss portion 31-4 to tighten and connect with the press under the connection head 32-2. There is known a configuration method. In the figure, 32-1 is a flow path of the branch pipe 32, 34
Is a fastening sleeve washer.

In such a common rail system employing a common rail and an injection pipe, the injection pipe provided between the common rail and the nozzle is designed to inject a sufficient amount into the combustion chamber without causing pressure loss in the common rail. In consideration of the convenience of piping, it is shorter. However, even with such a short injection pipe, pressure fluctuations occur in the injection pipe when the valve closes after fuel injection.
This pressure fluctuation causes pulsation, and the flow path 3 of the main pipe rail 31
1-1, and furthermore, it affects the injection pipe of the next cylinder through the branch hole 31-2, so that there is a problem that stable fuel injection cannot be performed.

[0004]

Problems to be solved by the invention are as follows.
For example, it is possible to reduce the pressure fluctuation by increasing the inner diameter of the main pipe rail 31 to increase the volume of the pipe, but there is a disadvantage that pulsation is transmitted quickly. Therefore, a method was developed in which an orifice was provided in the common rail to suppress pulsation and delay propagation. This method includes:
Branch hole 31- provided in the boss 31-4 of the main rail 31
8 to provide an orifice function by making the diameter smaller, and a branch hole 31-2 of the main rail 31 as shown in FIG.
A metal ring member (piece) 35 having an orifice having a pressing seat surface 35-1 and a pressure receiving seat surface 35-2 in the portion
A method of interposing between the pressure receiving seat surface 31-3 of 1-2 and the injection pipe connection head 32-2 is known, and any method can suppress pulsation and delay transmission. is there.
However, the method of imparting the orifice function by making the diameter of the branch hole smaller is to apply a high pressure repeatedly to the branch hole portion, so that the branch hole portion has a thickness of 7 mm or more even at the thinnest portion and further at a position deep from the boss end face. Therefore, there is a disadvantage that formation of an orifice is not easy. Further, the metal ring member (piece) 35 having an orifice is connected to the branch hole 31-2.
Between the pressure receiving seat surface 31-3 and the injection pipe connection head 32-2 by using an axial force of one fastening external screw nut 33 incorporated on the injection pipe side, that is, a branch hole. Pressure receiving seat surface 31-3 and pressing seat surface 3 of metal ring member 35
The disadvantage is that the stability of the seal is poor because it seals the seal part between the seal part with 5-1 and the seal part between the pressure receiving surface 35-2 of the metal ring member 35 and the pressing seat surface 32-3 of the injection pipe connection head. There is.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems. The object of the present invention is to prevent a metal ring member (piece) having an orifice from affecting the sealing performance, An object of the present invention is to provide a common rail injection pipe configured so that an axial force generated by a built-in fastening nut acts as a force for fixing a metal ring member.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a plurality of a main rails having a flow passage formed in the axial center thereof, the plurality of main rails being provided with a space therebetween in the axial direction. A common rail provided with a branch hole having a pressure receiving seat surface communicating with the flow passage and opening outward in the body boss portion or the separate body boss portion, and having a flow passage communicating with the flow passage and provided at an end thereof. An injection pipe or a shaft thereof, in which a pressing seat surface portion formed by a connection head is brought into contact with and engaged with the pressure receiving seat surface, and is connected by being tightened and connected with a press under the connection head neck by screwing a tightening nut. A common rail in which at least one connection hole portion provided in an axial peripheral wall portion of a main rail having a flow passage inside the core direction has a branch hole communicating with the flow passage and having a pressure receiving seat surface opening outward. And has a flow passage leading to the flow passage and provided at an end thereof. Injection in which a pressing seat surface portion formed by the continuation head is brought into abutment engagement with the pressure receiving seat surface, and is tightened and connected with the pressing under the connection head neck by screwing the connection hole portion and a tightening nut. The gist of the present invention is a common rail injection tube having a configuration in which a metal ring member having an orifice is embedded in the connection head.

That is, according to the present invention, a metal ring member having an orifice is buried inside a connection head of an injection pipe to constitute a connection head, so that the metal ring member serves only as an orifice to provide a sealing property. So that the axial force at the time of tightening and connecting with the pressing under the connection head neck by screwing of the tightening nut acts as a force for tightening the metal ring member. It is composed.

[0008]

1 and 2 show an example of a head of a common rail injection pipe according to the present invention. FIG. 1 shows an embodiment of a connection structure of a common rail injection pipe having an integrated boss portion. FIG. 2 is an explanatory view of a longitudinal section sequentially showing processing steps of forming the head of the common rail injection pipe shown in FIG. 1, and FIG. 3 is a connection structure of a common rail injection pipe having an integrated boss portion in the same manner. FIG. 4 is a longitudinal sectional view showing another embodiment of FIG.
Is an explanatory view in vertical section showing the processing steps of forming the head of the common rail injection pipe shown in FIG. 3 sequentially, and FIG. 5 is a vertical cross-sectional view showing one embodiment of a connection structure of the common rail injection pipe having a separate boss portion. FIG. 6 is a longitudinal sectional view showing an embodiment of a connection structure of a block rail type common rail injection pipe,
1, 11, 21 are main rails, 2a, 2b, 2c, 2d
Are injection tubes, 3a and 3b are metal ring members, 4, 14, and 2.
Reference numeral 3 denotes a fastening nut, and reference numerals 5 and 15 denote sleeve washers.

More specifically, the injection pipe for a common rail shown in FIG. 1 is provided with a plurality of bosses 1-4 provided at intervals on an axial peripheral wall of the main rail 1 made of a circular pipe. A branch hole 1-2 having a pressure receiving seat surface 1-3 that opens to the outside and opens to the outside of the flow passage 1-1 is formed, while the connection head 2a-2 has an orifice 3a on the injection pipe 2a side. -1
Embedded in a metal ring member 3a having
-2, the pressure seat surface 2a-3 is brought into contact with the pressure receiving seat surface 1-3 on the main pipe rail 1 side, and the tightening nut 4 previously assembled on the injection pipe side is attached to the boss portion 1-4. By screwing, the connection head 2a-2 is configured to be connected by being fastened together with pressing under the neck. In the drawing, reference numeral 2a-1 denotes a flow path of the injection pipe 2a.

The common rail injection pipe 2a is manufactured by a processing step shown in FIG. That is, as shown in (a), the portion of the head machining allowance of the thick steel pipe 2a-11 having a relatively small diameter, which has been cut into a fixed length in advance, is expanded by pipe expansion inside the mandrel member (not shown). Part 2a-1
2 is formed (b), and then a substantially bale-shaped metal ring member 3a having an orifice 3a-1 is fitted in the expanded tube portion 2a-12 (c), and the expanded peripheral wall portion is coaxially formed. The metal ring member 3a is buried by being pressed from the outside by a punch member (not shown) provided with a caulking mold (d), and is pressed by a punch member (not shown) provided with an occipital mold. The connection head 2a-2 is formed by processing the head to form a frusto-conical pressing seat surface 2a-3 on the mating seat portion on the peripheral surface, thereby obtaining the injection pipe 2a shown in (e). . Steps (d) and (e) can be performed simultaneously as desired.

FIGS. 1 and 2 exemplify a common rail injection tube using a substantially ring-shaped metal ring member 3a as a metal ring member embedded inside the connection head of the injection tube. FIGS. This is an example of a common rail injection tube using a normal cylindrical ring as a metal ring member. The connection configuration between the common rail and the injection tube is the same as in FIG. 1 except for the injection tube 2b in which a metal ring member 3b made of a cylindrical ring is embedded. The same is true. That is, in the common rail having the same configuration as that of FIG. 1, the orifice 3 is connected to the connection head 2b-2 on the side of the injection pipe 2b having the flow path 2b-1 communicating with the branch hole 1-2.
A cylindrical metal ring member 3b having b-1 is embedded, and a pressing seat surface 2b-3 formed by the connection head 2b-2 is brought into contact with and engaged with a pressure receiving seat surface 1-3 on the main pipe rail 1 side. By screwing a tightening nut 4 previously assembled on the injection pipe side to the boss portion 1-4, a connection structure is formed by tightening with a press under the connection head 2b-2 neck. ing.

As shown in FIG. 4, the common rail injection pipe 2b has a head processing allowance for a thick steel pipe 2b-11 (a) having a relatively small diameter and cut in advance to a fixed length. A large diameter portion 2b-12 is formed by rolling or cutting the portion (b), and then the expanded portion 2b-
A cylindrical metal ring member 3b having an orifice 3b-1 is fitted inside the portion 12 (c), and then the large diameter portion 2b-1
The portion 2 is coaxially processed by pressing with a punch member (not shown) provided with a caulking die to bury the metal ring member 3b (d), and a punch member (not shown) provided with an appropriate back head type The outer peripheral surface is formed into a frusto-conical pressing seat surface 2b-3 to the mating seat portion by pressing, thereby forming a connection head 2b-2, and the injection pipe 2b shown in (e). Is what you get.

Next, a connection structure of a common rail injection pipe having a separate boss portion shown in FIG. 5 includes an internal flow passage 11- provided in a peripheral wall portion on the side of the main rail 11 made of a circular pipe.
The use of a ring-shaped joint fitting 13 surrounding the outer peripheral portion of the main rail 11 near the pressure-receiving seat surface by forming a pressure-receiving seat surface 11-3 that opens outwardly from the branch hole 11-2 portion that leads to 1
The pressing seat surface 2c-3 formed by the connection head 2c-2 on the side of the injection pipe 2c similar to that described above is brought into contact with and engaged with the screw wall 13-1 protruding from the joint fitting 13 and the side of the injection pipe 2c beforehand. The connection head 2c-2 by screwing the tightening nut 14 incorporated in the
In this connection structure, the common rail injection pipe 2c is also similar to the injection pipe 2a shown in FIG. 4, for example, the connection head. Orifice 3b-1 in part 2c-2
Can be used. The cylindrical metal ring member 3b or the injection pipe 2c in which the metal ring member 3a is embedded can be used. 2c-1 is a flow path of the injection pipe 2c.

Further, the present invention can be applied to a block rail type common rail injection pipe as shown in FIG. In other words, the connection structure of the block / rail type common rail injection pipe shown in FIG. 6 is spaced apart from the peripheral wall in the axial direction on the main pipe rail 21 side composed of a block having a rectangular cross section having a flow passage 21-1 therein. A plurality of provided connection holes 21-4
A branch hole 21 having a pressure receiving seat surface 21-3 which opens to the outside and communicates with the flow passage 21-1 of the main rail 21 at the bottom of the main hole 21.
-2, and a connection head 2 on the side of the injection pipe 2d similar to the above.
The pressing seat surface 2d-3 formed by d-2 is brought into contact with and engaged with the pressure receiving seat surface 21-3 on the main pipe rail 21 side, and the external screw nut 23 for tightening previously assembled on the injection pipe 2d side is connected to the connection hole. Part 21
The connection head 2d-2 is screwed into the connection head 2d-2 so that the connection head 2d-2 is fastened in connection with the pressing under the neck. An injection tube 2d in which a cylindrical metal ring member 3b or metal ring member 3a is embedded can be used. 2d
-1 is a flow path of the injection pipe 2d. In addition, the main rail 21
The cross-sectional shape is not limited to a rectangle, but may be a triangle, a trapezoid, or the like.

The main rails 1, 11, and 21 as common rails are, for example, 28 mm in diameter and 9 mm in wall thickness.
A forged product made of material S45C or the like having a relatively thick tubular portion. The inside of the shaft core is formed as a flow passage by machining such as a boring gun drill, and a gap is maintained in the peripheral wall portion in the axial direction. A plurality of integrated bosses or separate bosses, or connection holes are provided. Further, the common rail having the integral boss portion is not limited to the connection structure described above, but a branch hole (not shown) leading to the flow passage is extended to near the free end of the boss portion, and the pressure receiving seat surface is set to the boss portion. The boss is formed so as to be exposed at the free end thereof, and a male screw is formed on the outer periphery of the boss portion, and a cap nut is screwed onto the male screw. It is needless to say that the present invention can be applied to a method of connecting and configuring.

[0016]

As described above, in the injection tube according to the present invention, the metal ring member having the orifice is embedded inside the connection head to form the connection head. The seal has a high stability because it only plays a role and does not affect the sealability, and the axial force when tightening and connecting together with the pressing under the connection head neck by screwing of the tightening nut is as described above. Since the metal ring member acts as a force for tightening the metal ring member, the metal ring member has an excellent effect of being able to reliably and stably exhibit an orifice function.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a connection structure of a common rail injection pipe having an integrated boss portion.

FIG. 2 is an explanatory view in vertical section showing a process of forming a head of the common rail injection pipe shown in FIG. 1 in order.

FIG. 3 is a longitudinal sectional view showing another embodiment of the connection structure of the common rail injection pipe having the integral boss portion.

FIG. 4 is an explanatory view in vertical section showing the processing steps of forming the head of the common rail injection pipe shown in FIG. 3 sequentially.

FIG. 5 is a longitudinal sectional view showing one embodiment of a connection structure of a common rail injection pipe having a separate boss portion.

FIG. 6 is a longitudinal sectional view showing one embodiment of a connection structure of a block / rail type common rail injection pipe.

FIG. 7 is a longitudinal sectional view showing one example of a conventional common rail injection pipe connection structure to which the present invention is applied.

FIG. 8 is a longitudinal sectional view showing an example of a pressure fluctuation suppressing means in the common rail injection pipe connection structure of the above.

[Explanation of symbols]

 1, 11, 21 Main rail 1-1, 11-1, 21-1 Flow passage 1-2, 11-2, 21-2 Branch hole 1-3, 11-3, 21-3 Pressure receiving seat surface 1- 4 Boss portions 2a, 2b, 2c, 2d Injection pipes 2a-1, 2b-1, 2c-1, 2d-1 Flow paths 2a-2, 2b-2, 2c-2, 2d-2 Connection head 2a-3 , 2b-3, 2c-3, 2d-3 Pressing bearing surface 3a, 3b Metal ring member 3a-1, 3b-1 Orifice 4, 14, 23 Tightening nut 5, 15 Sleeve washer

Claims (2)

[Claims] 1. A plurality of integral bosses or separate bosses provided at spaced intervals on an axial peripheral wall of a main rail having a flow passage in the axial center thereof, A common rail provided with a branch hole having a pressure receiving seat surface that opens to the outside and has a flow passage communicating with the flow passage, and a pressure seat surface portion formed by a connection head provided at an end thereof is provided on the pressure receiving seat surface. A metal ring member having an orifice in the connection head is embedded in the injection pipe which is brought into contact engagement and tightened and connected in accordance with the pressing under the connection head neck by screwing of a tightening nut. An injection tube for common rails. 2. A pressure receiving seat surface communicating with said flow passage and opening outwardly is formed in at least one connection hole portion provided in an axial peripheral wall portion of a main pipe rail having a flow passage inside the axial center thereof. A common rail provided with a branch hole having a flow passage communicating with the flow passage, and a pressing seat surface portion formed by a connection head provided at an end thereof is brought into contact with the pressure receiving seat surface to be engaged with the pressure receiving seat surface. In the injection pipe, which is fastened and connected in accordance with the pressing under the connection head neck by screwing of a fastening nut, a metal ring member having an orifice is embedded in the connection head. Injection tube for common rail.